This invention relates to an interlock for a partition assembly used to divide boxes and the like into a plurality of cells for containing and protecting various types of goods such as bottles, cans, and other containers.
Partition assemblies of this general type are well known in the art and generally include a set of longitudinal partition strips and a set of cross partition strips. Typically, the strips are of paperboard material and have interlocking slots such that the slots of the cross strips interlock with the slots of the longitudinal strips to provide a partition assembly. The interlocking slots are such that the partition assembly may be hinged between a fully opened configuration with the cross strips perpendicular to the longitudinal strips, and closed configurations with the partition assembly collapsed and the longitudinal and cross strips overlying one another. In other words, one set of strips may be hinged relative to the other set approximately 180.degree. so that the assembly may be collapsed in either of two collapsed positions.
In known partition assemblies, the interlocking strips may include corresponding tabs and tab receiving openings such that the tabs of one set of strips are received in and are retained within tab receiving openings of the other set of strips, thus "interlocking" the sets of strips together. One type of known assembly has such tabs near the edges of the strips and where the corresponding tab receiving openings are also at the edges. These are exemplified by Zeller U.S. Pat. No. 4,000,845. Other assemblies have the tabs and the tab receiving openings of the interlocking slots inwardly of the edges of the strips and may be characterized as "center lock" partitions as exemplified by U.S. Pat. Nos.: Bower 456,353, Herr 529,173, Williams 533,331, Carter 1,143,036, Navarro 1,528,341, Inman 1,894,402, and Raubenheimer 4,103,818 and 4,358,047.
Typically, partitions of the general type to which this invention relates are assembled and shipped to the customer in a collapsed configuration in a bundle. The customer may then use automatic equipment to extract the partition from the bundle, expand it, insert in into a box, and then load the box for shipment of goods. This means that the partition must hinge freely between collapsed and fully open configurations, the interlocks must not bind or distort or become disengaged during these operations, and yet the interlock design should provide for ease in assembly of the cross strips with the longitudinal strips into proper interfitting relation with automated assembly equipment. Thus, the problem is that an interlock design that holds the partition firmly together may not allow the longitudinal and cross strips to hinge freely or may be difficult to assemble, while one that is easy to assemble may have problems with holding together during the various operations.
The present invention provides an interlock for a partition assembly of a center lock type which may be readily assembled, which hinges freely between collapsed and opened configurations, and which is exceptional in retaining the interfitting strips in proper interlocking engagement during the various operations to which the assembly is subjected. In accordance with the invention, generally the interlock includes a slot in each interlocking strip, the longitudinal and cross strip. These slots open at the edges of the strips and extend inwardly to terminate within the strips. Each slot also includes a tab extending from a side edge of the slot and at least one of the slots has a tab retaining edge which engages the tab of the other slot. The tab of one of the slots has a base portion adjacent the edge of the slot from which it extends and a portion laterally of the base portion which protrudes into the slot. A portion of the tab laterally of the base portion extends longitudinally (in the direction of the slot or along the hinge axis) beyond the base portion, and preferably is generally of a butterfly design having wings of an overall length greater than the base. The butterfly tab overlaps at least a portion of the strip with which it interlocks in both of the two collapsed configurations, and also aids in holding the partition assembly in the proper interlocked condition with the assembly open. The improved interlock design of the present invention allows ease in assembly and hinges freely between collapsed and open configurations.
These and other objects and advantages of the invention are apparent from the drawing and detailed description to follow.